What are the management options for a 56-year-old patient with X-linked hypophosphatemia (XLH) presenting with hypophosphatemia and normal calcium levels, complaining of generalized aches and pains?

From the Guidelines

For a 56-year-old patient with X-linked hypophosphatemia (XLH) presenting with hypophosphatemia and normal calcium levels, complaining of generalized aches and pains, I strongly recommend initiating treatment with active vitamin D together with oral phosphorus (phosphate salts) to reduce osteomalacia and its consequences and to improve oral health, as suggested by the clinical practice recommendations for the diagnosis and management of X-linked hypophosphatemia 1. The patient's symptoms likely result from chronic hypophosphatemia causing osteomalacia and inadequate mineralization of bone.

• Treatment aims to normalize phosphate levels, improve bone mineralization, and alleviate pain.
• The recommended dose range for phosphate is 750–1,600mg daily (based on elemental phosphorus) and for calcitriol is 0.50–0.75μg daily, as per the guidelines 1.
• It is essential to use substantially lower doses of active vitamin D and oral phosphate than are used in children, as recommended by the guidelines 1.
• Regular monitoring is crucial, including serum phosphate, calcium, PTH, and renal function every 2-3 months initially, then quarterly once stable.
• The patient should be counseled that response may take several weeks to months, and that compliance with the multiple daily doses of phosphate is crucial for symptom improvement.
• Additionally, ensuring normal calcium intake and supplementing patients with native vitamin D (cholecalciferol or ergocalciferol) in case of vitamin D deficiency is also recommended, as suggested by the guidelines 1.

From the FDA Drug Label

CRYSVITA is indicated for the treatment of X-linked hypophosphatemia (XLH) in adult and pediatric patients 6 months of age and older. Discontinue oral phosphate and/or active vitamin D analogs (e. g. calcitriol, paricalcitol, doxercalciferol, calcifediol) 1 week prior to initiation of treatment The recommended starting dose regimen is 0. 8 mg/kg of body weight, rounded to the nearest 10 mg, administered every two weeks.

The management option for a 56-year-old patient with X-linked hypophosphatemia (XLH) presenting with hypophosphatemia and normal calcium levels is burosumab (CRYSVITA) treatment. The patient should discontinue any oral phosphate and/or active vitamin D analogs 1 week prior to initiation of treatment. The recommended starting dose is 0.8 mg/kg of body weight, administered every two weeks, with dose adjustments as needed to maintain serum phosphorus within the reference range for age 2.

From the Research

Management Options for X-linked Hypophosphatemia (XLH)

The patient's condition, X-linked hypophosphatemia (XLH), is characterized by hypophosphatemia and normal calcium levels, presenting with generalized aches and pains. The management options for this condition can be considered as follows:

• Phosphate Supplementation: Oral phosphate supplements in combination with calcitriol are the mainstay of treatment for XLH, as indicated by 3. This approach aims to correct the phosphate deficiency and alleviate symptoms.
• Treatment of Underlying Condition: The treatment should also focus on addressing the underlying cause of XLH, which is a genetic disorder affecting renal phosphate reabsorption, as mentioned in 3.
• Monitoring and Adjustment: The patient's phosphate levels, calcium levels, and overall clinical condition should be closely monitored, and the treatment regimen adjusted as necessary to ensure optimal management of the condition, as suggested by 4.
• Consideration of Comorbid Conditions: The presence of any comorbid conditions, such as kidney disease or malnutrition, should be taken into account when developing a treatment plan, as noted in 4.

Treatment Approaches

The following treatment approaches can be considered for the patient:

• Oral Phosphate Supplements: Oral phosphate supplements can be used to correct mild to moderate hypophosphatemia, as indicated by 4.
• Intravenous Phosphate Supplementation: Intravenous phosphate supplementation may be necessary in cases of severe hypophosphatemia or when oral supplementation is not effective, as mentioned in 3.
• Active Vitamin D: Active vitamin D, such as calcitriol, can be used in conjunction with phosphate supplements to enhance phosphate absorption and correct vitamin D deficiency, as noted in 4.

Future Treatment Options

Future treatment options for XLH may include novel therapies aimed at addressing the underlying genetic defect or improving phosphate homeostasis, such as those discussed in 5. However, these options are still under investigation and not yet widely available.